1. Field of the Invention
This invention relates to a photographic light-sensitive material in which the use of organic substances which may cause environmental pollution in the steps of the production and of the development processing is eliminated and, more particularly, it relates to a photographic light-sensitive material containing surface active agents having no toxic physiological action and high biodegradability applied in such a manner that they exhibit excellent properties as a coating aid and as an aid for dispersing photographic additives in a light-sensitive silver halide emulsion.
2. Description of the Prior Art
In the production of a photographic light-sensitive materials, anionic, nonionic, cationic or amphoteric surface active agents are used as a coating aid, a dispersing agent, an antistatic agent, a setting agent, an agent for modifying the physical properties of interfaces, an agent for modifying the properties of a light-sensitive silver halide such as a sensitizer or an infectious development accelerator, and further photographic additives such as sensitizing dyes, antifogging agents, couplers, ultra-violet absorbants, antioxidants or dyes. Of all of these, anionic surface active agents are used in great quantities. Since a large quantity of anionic surface active agents is used also in fields other than the photographic fields, it is all the more important to develop improved techniques for overcoming environmental pollution caused by such surface active agents.
Of the anionic surface active agents used in the production of photographic light-sensitive materials, those used in the dispersion of photographic additives in a light-sensitive silver halide emulsion should, particularly, be selected carefully, regarding their performance such as their dispersibility relative to the material to be dispersed and their influence on the essential properties of the additives.
In order to disperse photographic additives, particularly, hydrophobic couplers and ultraviolet absorbants, the salts of alkylbenzenesulfonic acids or the salts of alkylnaphthalenesulfonic acids have been used. These agents are described in, e.g., Japanese Patent Publication Nos. 4293/64 and 4547/71, U.S. Pat. Nos. 2,322,027; 2,360,289; 2,801,170; 2,801,171; 2,852,382; 2,949,360; 3,396,027 and 3,619,195, German Patent Nos. 1,143,707; 2,045,414; 2,043,271 and 2,045,464. However, surface active agents which have aromatic rings are more or less disadvantageous with respect to the biodegradability and their effects on physiological action. Also, saponin has been used, as described in, for instance, British Patent Nos. 1,098,594; 1,099,415; 1,099,416 and 1,099,417. However, saponin is unsuitable because of its poor properties for dispersing photographic additives, its poor adaptability to high-speed coating of a silver halide emulsion in high concentration in conformity with present techniques, and insufficient shelf life for the preparation of a dispersion of photographic additives in high concentration. Furthermore, aliphatic sulfuric acid esters have been used, as described in, e.g., U.S. Pat. Nos. 2,304,940; 2,311,021; 2,322,027 and 2,533,514. These sulfuric acid esters tend to be hydrolyzed and, particularly, straight chain alkyl sulfuric acid esters tend to be inferior to salts of alkylbenzenesulfonic acids in dispersability when used alone as an anionic surface active agent. Mostly, they are used together with nonionic surface active agents to correct this defect, as described in, e.g., German Patent Nos. 1,942,873.
The method of solubilizing photographic additives in an aqueous solution of anionic surface active agents and then adding the same to a light-sensitive emulsion is known, as described in, e.g., U.S. Pat. No. 3,822,135. However, no clear descriptions are found in this specification as to surface active agents of the present invention. In this previously disclosed method, the salts of alkylbenzenesulfonic acids are also preferred, but they are not always desirable with respect to physiological effects and biodegradability.